Living Control Mechanisms 13.10.22

Question 1

What is homeostasis?

Answer 1

Maintenance of a constant internal environment so it can function properly in the face of external factors.

Question 2

What are the steps of homeostasis?

Answer 2

Control centre (detects change), effector, regulated variable, sensor in a loop, all connected

Question 3

What are some examples of homeostasis?

Answer 3

temperature, potassium, glucose, blood oxygen, hydrogen ion

Question 4

What is the endocrine communication system?

Answer 4

Hormones to communicate

Question 5

What is the nervous communication system?

Answer 5

electrical impulses in order to communicated

Question 6

What is autocrine communication?

Answer 6

Cell is communicating with itself. Cell sends a signal and the signal goes to a receptor, which is on the same cell.

Question 7

What is the paracrine communication?

Answer 7

Cell sends a signal, diffuses across gap. This is with neighbouring cells that are a short distance away. Inactivated locally, so doesn’t even enter the blood stream.

Question 8

Give an example of paracrine communication

Answer 8

Interleukins (IL):
- signalling in the immune system
- mainly between white blood cells
Platelet derived growth factor (PDGF):
- released from platelets
- regulates cell growth

Question 9

What is endocrine system commmunication?

Answer 9

Cells communicating to other cels elsewhere in the body. Signal must travel in the blood stream. Hormones carrying the signal.

Question 10

Which organs and glands are endocrine?

Answer 10

• hypothalamus (brain)
• pituitary (brain)
• thyroid (neck)
• adrenals (kidneys)
• pancreas (abdomen)
• ovaries
• testes

Question 11

What is a hormone?

Answer 11

Molecule that acts as a chemical messenger
They are classified according to their structure:
- amino-acid derivatives
- peptide
- steroid

Question 12

What is an amino-acid hormone?

Answer 12

• simple type of hormone
• synthesised from tyrosine
• E.g. adrenaline

Question 13

What is a peptide hormone?

Answer 13

• made of amino acids
• vary in size from few amino acids to small proteins
• some have carbohydrates side chains (glycoproteins)
• Hydrophilic (like water)

Question 14

What do peptide and amino acid hormones do?

Answer 14

Produce a quick reaction in the body

Question 15

Peptide hormone example of how it is transported

Answer 15

TSH (thyroid stimulating hormone)
- Released from pituitary and stimulates the thyroid gland.
- Hormone pre-made and stored in cell ready to be released when needed.
- Hormone dissolved in blood.
- Receptor on the other cell membrane.
- Chemical reaction produces quick response from cell (signal transduction cascade)

Question 16

What are steroid hormones?

Answer 16

• made from cholesterol
• different enzymes modify molecule to produce a variety of hormones
• can’t dissolve in water
• can dissolve in lipids

Question 17

How do steroid hormones work?

Answer 17

Work very slowly and have a slow response e.g. testosterone

Question 18

Example of steroid hormones and stages of it

Answer 18

E.g. testosterone
- Testosterone made by cell and diffuses out once made (not stored)
- transported in blood bound to transport protein as can’t dissolve in water
- receptor is in the target cell (not on cell membrane)
- Slow responses as directly affects DNA

Question 19

What is the feedback system with the endocrine system?

Answer 19

Feedback loops e.g. positive and negative

Question 20

What is a positive feedback loop?

Answer 20

Signal is amplified

Question 21

What is a negative feedback loop?

Answer 21

E.g. pituitary gland
- Anterior Pituitary releases TSH to thyroid
- Then another hormone released (thyroxine)
- Higher the level of thyroxine, more inhibition on the pituitary
- Decrease of TSH and keeps target cell level.
- If thyroxine goes down, removes inhibition and so more TSH made.